Subject: PPC4xx memory to memory DMA

From: padmanabha <[email-masked]>
Date: Tue, 08 Jan 2008 15:23:16 +0530

Hi,

I  am using 2.6.23  kernel for ppc 440spe based board. When i tried 
memory to memory DMA  ( please find  the code given below )
 DMA is not happening.

I am trying the same for last few days.... without any success.  Can any 
one guide me.

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/delay.h>

#include<asm/ppc4xx_dma.h>
#include<asm/io.h>
#include<linux/slab.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PPC4xx Mem to Mem DMA  demo");
MODULE_AUTHOR("[email-masked]");

extern void flush_dcache_all(void);

#define DMA_CHANNEL_NUM                         0
#define SIZE                                                    4096

ppc_dma_ch_t  ppc_dma_channel;
ppc_dma_ch_t p_init;

void * vir_dst_addr;
void * vir_src_addr;

unsigned long int  phy_src;
unsigned long int  phy_dst;

int ret, offset;

void dma_trns(void)
{

      memset( (char *)&p_init, 0, sizeof(p_init));

      p_init.polarity = 0;
      p_init.pwidth   = PW_8;

      ret = ppc4xx_init_dma_channel( DMA_CHANNEL_NUM, &p_init);

      if (ret  ==   DMA_STATUS_GOOD)
      {
          printk("%s: init_dma_channel return %d, dest is 
%p\n",__FUNCTION__, ret, vir_dst_addr);
      }

      else if(ret  ==   DMA_STATUS_BAD_CHANNEL)
      {

        printk("TS2: bad channel \n");

      }

      flush_dcache_all();

      ppc4xx_clr_dma_status( DMA_CHANNEL_NUM);

      ppc4xx_set_dma_mode(DMA_CHANNEL_NUM,DMA_MODE_MM);
      ppc4xx_set_src_addr( DMA_CHANNEL_NUM, (phys_addr_t) phy_src);
      ppc4xx_set_dst_addr(DMA_CHANNEL_NUM,  (phys_addr_t) phy_dst);
      ppc4xx_set_dma_count(DMA_CHANNEL_NUM,(SIZE * 2 ));

      ppc4xx_set_channel_priority(DMA_CHANNEL_NUM,PRIORITY_HIGH);

      ppc4xx_enable_dma(DMA_CHANNEL_NUM);

      // wait till completion of DMA

       while( 1)
       {
            mdelay(100);

            ret = 1;
            ret = ppc4xx_get_dma_residue( DMA_CHANNEL_NUM);

            if( ret == 0)
            {
                printk(" no dma operation is pending\n");
                break;
            }

       }

     ppc4xx_disable_dma( DMA_CHANNEL_NUM);

    return  ;
}

static int dma_test_init(void)
{

    vir_src_addr = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, 1);

    if( vir_src_addr == NULL )
    {
        printk( " Memory not allocated\n");
        return 1;
    }
    printk("%s: virtual address for src buffer is 0x%p \n",__FUNCTION__, 
(unsigned int *)vir_src_addr);
    memset( (unsigned long *)vir_src_addr, 0x55, sizeof(unsigned long) * 
(SIZE *2));

#if SRC_DISPLAY

    ret = 0;

    while(ret < 100)
    {

        printk( "%s: value at virtual addr 0x%p is 0x%X \n", 
__FUNCTION__,( (unsigned int *)vir_src_addr + ret ),\

        *( (unsigned int *)vir_src_addr + ret));

        ret++;

    }

#endif

    vir_dst_addr = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA,1);

    if( vir_dst_addr == NULL )
    {
        printk( " Memory not allocated\n");
        free_pages( (unsigned long)vir_src_addr, 1);
        return 1;
    }
    printk("%s: virtual address for dst buffer is 0x%p 
\n",__FUNCTION__,(unsigned int *)vir_dst_addr);
    memset( (unsigned long *)vir_dst_addr, 0, sizeof(unsigned long) * 
(SIZE *2));

#if DST_DISPLAY

    ret = 0;
    while(ret < 100)
    {

        printk( "%s: value at virtual addr 0x%p is 0x%X \n", 
__FUNCTION__,( (unsigned int *)vir_dst_addr + ret ),\
        *( (unsigned int *)vir_dst_addr + ret));

        ret++;

    }
#endif

//      phy_src = virt_to_bus(vir_src_addr);
//      phy_dst = virt_to_bus(vir_dst_addr);

      phy_src = iopa( (unsigned long ) vir_src_addr);
      phy_dst =  iopa(  (unsigned long )vir_dst_addr);

    dma_trns();

      ret = 1;
      ret = ppc4xx_get_dma_residue( DMA_CHANNEL_NUM);
      if( ret == 0)
      {
          printk(" no dma operation is pending\n");

      }

    return 0;
}

void dma_test_exit(void)
{
      ret = ppc4xx_get_channel_config( DMA_CHANNEL_NUM, &ppc_dma_channel);

      if( ret != DMA_STATUS_GOOD )
      {
         printk("TS2: DMA STATUS  is not good \n");
      }
      else
      {
         printk("TS2:  DMA STATUS  good \n");

      }

      ret = 0;

      while(ret < 100)
      {

         printk( "%s: value at virtual addr 0x%p after dma is 0x%X \n", 
__FUNCTION__,( (unsigned int *)vir_dst_addr + ret ), \
         *( (unsigned int *)vir_dst_addr + ret)) ;

         ret++;
      }

     mdelay(100);

     free_pages( (unsigned long)vir_src_addr, 1);
     free_pages( (unsigned long)vir_dst_addr, 1);

}

module_init(dma_test_init);
module_exit(dma_test_exit);

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Thanks and Regards,
Padmanabha.s